Tortenboden (plain sponge cake base)

Method

1. Whisk the eggs, sugar and salt together with an electric whisk on high speed for 5 to 6 minutes, until pale, thick and roughly tripled in volume; the mixture should hold a ribbon on the surface for a few seconds when the whisk is lifted.
2. Sift the flour, cornstarch and baking powder together, then sift a third of it over the egg mixture and fold in gently with a large spatula. Repeat with the remaining flour in two more additions, folding just until no dry streaks remain.
3. Pour into a lined 26 cm springform and smooth the top. Bake at 175°C for 22 to 25 minutes, until it springs back when pressed and a skewer comes out clean.
4. Cool in the tin for 10 minutes, then turn out onto a rack, peel off the lining paper, and cool completely before slicing into layers.

Notes

• Whip the eggs properly before the flour goes in. This sponge has no other leavening beyond the whipped air and a small amount of baking powder, and an undersized ribbon stage gives a flat, dense sponge no amount of baking powder will fix.
• Fold gently, not vigorously. Beating the flour in deflates the whipped eggs and undoes the work of the first step; a few decisive folds are better than many rough ones.
• This sponge is deliberately plain and dry-ish on its own. It is meant to take on syrup, cream or filling in a layer cake, not to be eaten unadorned.
• It keeps for 2 days at room temperature, wrapped, and freezes well for up to 2 months, which makes it worth baking a spare when you have the oven on anyway.

Ingredient substitutions

• A splash of vanilla extract or lemon zest can be whisked in with the eggs for a base with more character on its own.
• For a chocolate version, replace 30 g of the flour with 30 g of cocoa powder, sifted in with the rest of the dry ingredients.
• This base has no dairy or nuts in it, which makes it a useful starting point for building an allergy-friendly layer cake.
• Split into two thinner layers, this same batter also works baked in two 20 cm tins for about 18 minutes each, if a specific torte calls for thinner sponge.